1. Technical Field
The present invention generally relates to a brush copolymer and a biomedical device such as an ophthalmic lens having a brush copolymer coating on at least a portion of a surface thereof.
2. Description of Related Art
Medical devices such as ophthalmic lenses made from, for example, silicone-containing materials, have been investigated for a number of years. Such materials can generally be subdivided into two major classes, namely, hydrogels and non-hydrogels. Hydrogels can absorb and retain water in an equilibrium state, whereas non-hydrogels do not absorb appreciable amounts of water. Regardless of their water content, both hydrogel and non-hydrogel silicone medical devices tend to have relatively hydrophobic, non-wettable surfaces that have a high affinity for lipids. This problem is of particular concern with contact lenses.
Those skilled in the art have long recognized the need for modifying the surface of such silicone contact lenses so that they are compatible with the eye. It is known that increased hydrophilicity of the lens surface improves the wettability of the contact lens. This, in turn, is associated with improved wear comfort of contact lenses. Additionally, the surface of the lens can affect the lens's susceptibility to deposition, particularly the deposition of proteins and lipids resulting from tear fluid during lens wear. Accumulated deposition can cause eye discomfort or even inflammation. In the case of extended wear lenses (i.e., lenses used without daily removal of the lens before sleep), the surface is especially important, since extended wear lenses must be designed for high standards of comfort and biocompatibility over an extended period of time.
Silicone lenses have been subjected to plasma surface treatment to improve their surface properties, e.g., surfaces have been rendered more hydrophilic, deposit resistant, scratch-resistant, or otherwise modified. Examples of previously disclosed plasma surface treatments include subjecting the surface of a contact lens to a plasma containing an inert gas or oxygen (see, for example, U.S. Pat. Nos. 4,055,378; 4,122,942; and 4,214,014); various hydrocarbon monomers (see, for example, U.S. Pat. No. 4,143,949); and combinations of oxidizing agents and hydrocarbons such as water and ethanol (see, for example, WO 95/04609 and U.S. Pat. No. 4,632,844). U.S. Pat. No. 4,312,575 discloses a process for providing a barrier coating on a silicone or polyurethane lens by subjecting the lens to an electrical glow discharge (plasma) process conducted by first subjecting the lens to a hydrocarbon atmosphere followed by subjecting the lens to oxygen during flow discharge, thereby increasing the hydrophilicity of the lens surface.
U.S. Pat. No. 6,582,754 (“the '754 patent”) discloses a process for coating a material surface involving the steps of (a) providing an organic bulk material having functional groups on its surface; (b) covalently binding to the surface of the bulk material a layer of a first compound having a first reactive group and an ethylenically unsaturated double bond by reacting the function groups on the surface of the bulk material with the first reactive group of the first compound; (c) copolymerizing, on the surface of the bulk material, a first hydrophilic monomer and a monomer comprising a second reactive group to form a coating comprising a plurality of primary polymer chains which are covalently bonded to the surface through the first compound, wherein each primary polymer chain comprises second reactive; (d) reacting the second reactive groups of the primary polymer chains with a second compound comprising an ethylenically unsaturated double bond and a third reactive group that is co-reactive with the second reactive group, to covalently bind the second compound to the primary polymer chains; and (e) graft-polymerizing a second hydrophilic monomer to obtain a branched hydrophilic coating on the surface of the bulk material, wherein the branched hydrophilic coating comprises the plurality of the primary polymer chains and a plurality of secondary chains each of which is covalently attached through the second compound to one of the primary chains. The process disclosed in the '754 patent is time consuming as it involves multiple steps and uses many reagents in producing the coating on the substrate.
Blister packages and glass vials are typically used to individually package each soft contact lens for sale to a customer. Saline or deionized water is commonly used to store the lens in the packages, as mentioned in various patents related to the packaging or manufacturing of contact lenses. Because lens material may tend to stick to itself and to the lens package, packaging solutions for blister packs have sometimes been formulated to reduce or eliminate lens folding and sticking; packaging solutions may include a polymer to improve comfort of the contact lens. Polyvinyl alcohol (PVA) has been used in contact lens packaging solutions. Additionally, U.S. Pat. No. 6,440,366 discloses contact lens packaging solutions comprising polyethylene oxide (PEO)/polypropylene oxide (PPO) block copolymers, especially poloxamers or poloxamines.
U.S. Patent Application Publication No. 20080151181 (“the '181 application), commonly assigned to assignee herein Bausch & Lomb Incorporated, discloses a contact lens having its surfaces coated with an inner layer and an outer layer, the inner layer comprising a polymer comprising monomeric units derived from an ethylenically unsaturated monomer containing a boronic acid moiety, and the outer layer comprising a diol. The '181 application further discloses that the diol layer includes at least one diol-terminated polymer member selected from the group consisting of diol-terminated polyvinyl pyrrolidinone, diol-terminated polyacrylamides, diol-terminated polyethylene oxides, and diol-terminated polyethylene oxide (PEO)/polypropylene oxide (PPO) block copolymers.
It would be desirable to provide improved surface modified biomedical devices having an optically clear, hydrophilic coating on the surface thereof that renders the device more biocompatible. In addition, it would also be desirable to form a coating on a contact lens having improved wettability and lubriciousness while also inhibiting attachment of microorganisms to the surface of the lens, thus making the lens more comfortable to wear for a longer period of time. In this manner, the biocompatibilized lens can be capable of continuous wear overnight, preferably for a week or more without adverse effects to the cornea.